1. Field of the Invention
The present invention relates to a card connector, and more particularly to a card connector having a function of half-locking a card such as a memory card inserted into a card insertion space of a case, in an extractable state.
2. Description of the Prior Art
In some of card connectors, a card insertion space is formed by a case having contact pieces corresponding to card terminals, a slider that is to be pushed in by a card inserted into the card insertion space is placed at a position adjacent to the card insertion space, and the slider is elastically urged in a card ejecting direction. Among such card connectors, a card connector having functions of locking the slider pushed by a card to the case, and half-locking the card to the slider is well known.
In a prior art example of card connectors of the this type, a half-lock mechanism for half-locking a card to a slider is formed by a plate spring made of a sheet metal. Such a card connector is configured so that a mountain-like engaging portion is formed by bending a tip end portion of a plate spring which is held by the slider in a cantilevered manner, and the engaging portion rides over a side end face of a card inserted into the card insertion space to be fitted into a recess formed in a side end portion of the card, whereby the card is half-locked to the slider in an extractable manner (for example, see Japanese Patent Application Laying-Open No. 11-135192). In another prior art example, a cam is provided to an end portion of a spring member which is molded of a resin or the like, a card inserted into a card insertion space pushes the cam to displace the spring member, and, after the displacement, the spring member conducts a returning operation to collide against a side wall of a portion accommodating the spring member, thereby generating a click sound, and, on the basis of the click sound, the operator can know the completion of the connection between the card and a connector (for example, see Japanese Utility Model Publication No. 7-55641).
By contrast, a card which is a sue object of a card connector is usually configured so that the outer shell is formed by molding of a resin. In the prior art examples described above, therefore, the engaging portion of the sheet metal made plate spring, and the resin-made cam which are used for half-locking rub against the resin face of the outer shell of the card.
In a further prior art example, a half-lock mechanism for half-locking a card to a slider is formed by a plate spring made of a sheet metal. In the prior art example, when the slider is at a pushed position, the rearward displacement of an engaging portion formed in the tip end of the plate spring is restricted by a side wall face of a case, and, when the slider is at a stand-by position, the engaging portion is placed so as to correspond to an opening formed in the side wall face of the case, whereby the restriction of the rearward displacement of the engaging portion is eliminated, and, when the slider is at the pushed position, the card is prevented from being forcedly extracted (for example, see Japanese Patent Application Laying-Open No. 2001-118633). In the prior art example, during a process of ejecting the card, the card cannot be prevented from popping out because of the elimination of the rearward displacement restriction of the engaging portion in the case where the slider is at the pushed position. In order to cope with this situation, therefore, a free end of an auxiliary plate spring faces to the opening which is formed in the side wall face of the case to eliminate the rearward displacement restriction of the engaging portion, and the free end of the auxiliary plate spring is elastically contacted with the engaging portion, so that the elastic force of the plate spring when the slider is at the stand-by position is increased.
In the prior art example (Japanese Patent Application Laying-Open No. 11-135192), when operations of inserting and ejecting a card are repeated and the engaging portion of the sheet metal made plate spring repeatedly rubs against the resin face of the outer shell of the card, there arises a situation where the outer shell of the card which is made of a resin is shaved off by the engaging portion made of a metal. Therefore, the card holding force exerted by the engaging portion which is fitted into the recess of the card is remarkably reduced, and the half-lock function performed by the half-lock mechanism is impaired in an early stage. As a result, the initial half-lock performance is hardly maintained for a long term.
Therefore, it may be contemplated that the sheet metal made plate spring is replaced with a spring member molded of a resin as in the other prior art example (Japanese Utility Model Publication No. 7-55641), and the engaging portion is formed integrally with the spring member. According to the configuration, since the engaging portion is made of a resin, the outer shell of the card is not shaved off by the engaging portion even when the engaging portion repeatedly rubs against the resin face of the outer shell of the card.
When the sheet metal plate spring is simply replaced with a spring member molded of a resin, however, it is difficult to provide the spring member with a displacement amount sufficient for absorbing dispersions in the size and width of a card, and those of the production accuracy of the card connector itself, and also with a card holding force in a half-locked state. Specifically, a resin itself forming the spring member is poorer in elasticity than the sheet metal made plate spring, and the spring member molded of a resin has a tendency that loads are hardly dispersed during elastic deformation and stresses are concentrated only to one place of a basal end portion of the spring member. Consequently, there arises a situation where repetitive deformations due to insertion and extraction of a card causes the spring member to be plastically deformed in an early stage. As a result, it is difficult to maintain the half-lock performance for a long term.
In order to prevent the card in a card-set state from being forcedly extracted, it is advantageous to hold the card by a large force. When a half-locking force, i.e., the spring force of the plate spring in which the engaging portion is formed in the tip end is simply increased, the friction between the engaging portion of the sheet metal made plate spring and the resin face of the outer shell of the card is further increased. Consequently, the half-lock performance is drastically lowered. Moreover, the insertion and extraction resistance of the card in the state where the slider is at the stand-by position is large. Therefore, it is difficult to insert and extract the card, and, when the card is inserted, the slider is moved, whereby the insertion feeling is impaired.
The invention has been conducted in view of the above-discussed circumstances. It is an object of the invention to provide a card connector which is based on the concept that, among elements of a half-lock mechanism, a component(s) which is to rub against a card is molded of a resin, and a component(s) which is requested to exert an elastic function is made of a metal, and in which the initial half-lock performance can be maintained for a long term.
It is another object of the invention to provide a card connector into which a half-lock mechanism can be incorporated with using a small space that can be ensured in a slider.
It is a further object of the invention to provide a card connector into which a half-lock mechanism can be incorporated with using a small space that can be ensured in a slider, and in which the durability of a component(s) that is molded of a resin is enhanced.
It is a still further object of the invention to provide a card connector into which a half-lock mechanism can be incorporated with using a small space that can be ensured in a slider, and in which a component(s) that is made of a metal can exert a stable elastic function.
It is a still further object of the invention to provide a card connector which can improve a half-locking force in a card-set state while attaining the above-mentioned objects.